With increasing industrial development, digitalized office technologies have experienced great growth and are now rapidly gaining in popularity. For example, a diversity of office machines such as copy machines, printers, fax machines and scanners (also referred as single-function peripherals) are utilized to achieve various purposes. The diverse office machines, however, occupy lots of space. Nowadays, a multifunction peripheral having multiple functions in one structural unit, for example the functions of a printer, a scanner, a fax machine and/or a copy machine, is thus developed. As a consequence, the processing capability of the multifunction peripheral is increased and the operative space thereof is reduced.
For successively and continuously feeding many paper sheets, the single-function peripheral or the multifunction peripheral usually has an automatic document feeder (ADF). After a stack of paper sheets to be scanned are placed on the sheet feeding tray, the sheet-feeding mechanism of the auto document feeder will successively fed the paper sheets into the inner portion of the office machine so as to implement associated operations such as scanning, faxing, scanning operations and the like. The automatic document feeder has a sheet separating device for separating only a single paper sheet from the stack of paper sheets, so that a single paper sheet is allowed to be fed into the inner portion of the office machine at each time. In addition, the automatic document feeder has a sheet stopping mechanism. The front edges of the paper sheets are stopped by the sheet stopping mechanism from being transported into an entrance of a sheet-guiding path before the sheet-feeding operation is done.
FIG. 1 is a schematic view illustrating a sheet stopping mechanism of a conventional automatic document feeder. The sheet stopping mechanism comprises a restraining part 11 and a stopping part 12. By restraining rotation of the stopping part 12, the front edges of the paper sheets 13 are hindered by the lower end 121 of the stopping part 12 in order to achieving the sheet stopping purpose. For feeding the paper sheet into the entrance of the sheet-guiding path, the restraining part 11 is rotated with respect to the axle center 122 by a specified angle. Upon rotation of the restraining part 11, the lower end 121 of the stopping part 12 is ascended and thus the paper sheet is allowed to feed into the entrance of the sheet-guiding path. After the sheet-feeding operation is completed, the stopping part 12 returns to its original position due to the weight thereof.
The sheet stopping mechanism of the conventional automatic document feeder, however, still has some drawbacks. For example, the upper cover needs to be opened if the automatic document feeder is suffered from a breakdown. During the upper cover is closed, the paper sheets are possibly pierced through. Since the stopping part is lowered to a sheet-stopping position according to the weight of the stopping part after the sheet-feeding operation is completed, the weight of the stopping part should be elaborately designed and controlled. Moreover, if the stopping part has a feathering edge resulting from the fabricating process, the stopping part fails to be normally operated.
Therefore, there is a need of providing an improved sheet stopping mechanism so as to obviate the drawbacks encountered from the prior art.